1. Field of the Invention
The present invention relates generally to antenna systems and, more particularly, to a system and method for using a single antenna for active and passive radio functions.
2. Introduction
Portable wireless devices continue to proliferate in today's technology-driven market. Advances in computing technology and manufacturing processes have resulted in a dramatic lowering of the costs of such devices. For passive radio systems such as the radio frequency identification (RFID) system, it is now typical that the antenna is one of the most expensive components.
In general, RFID tags can transmit data such as identification information, location information, or information about the tagged product (e.g., price, color, date of purchase, etc.) to a tag reader. RFID tags have therefore proved useful in various tracking and access applications. Passive RFID tags require no internal power source because the minute electrical current induced in the antenna by the incoming RF signal provides enough power for the RFID tag circuitry to power up and transmit a response.
It is often desirable to include passive RFID tags in equipment that would normally be powered from an active power source such as a battery, electrical mains, or solar cells. The passive RFID tags can provide location, identification, or other information about the device during times when the active power source is not available such as during manufacturing, assembly, packaging, shipping, etc. As use of RFID technology continues to expand in the marketplace, a cost-effective mechanism is needed to integrate the technology in active devices.